Symptoms: Rust usually occurs in late summer, following hot, dry periods when grass growth has slowed. Severe rusting indicates inadequate fertilization. Infrequent mowing intervals result in a buildup of rust pustules on leaves and stems.
Solutions: Use rust-resistant cultivars such as Turf Alive! or Turf Alive! III. Avoid Merion Kentucky bluegrass which is very susceptible. Use a balanced, slow-release fertilizer like Lawns Alive! or WOW! Plus. Avoid evening watering. As needed, spray Soap-Shield at 7-10 day intervals.
Symptoms: On closely cut turf, the disease appears as small circular patches of bleached grass, ranging from dime-size to silver-dollar-size. The presence of dollar spot may signal a nutritionally deficient turf. Warm days and cool nights that result in heavy dews favor the disease. The fungus overwinters in thatch.
Solutions: Use Lawns Alive! or WOW! Plus to meet nutritional needs of turf. Water infrequently but deeply, preferably in the morning so grass blades will dry before nightfall. Sow Turf Alive! or Turf Alive! III, which do not form thatch, to reduce overwinter sites for the fungus. Apply Soap-Shield at first appearance in areas where dollar spot has been a problem.
Symptoms: Powdery mildew is most serious on new seedlings or in shady locations where light intensity and air movement are limited. The disease overwinters in thatch and in infected plants. The spores are spread by air currents and become active when the air temperature approaches 65oF and humidity is high. Unlike other pathogens, powdery mildew does not need the presence of surface water for infection.
Solutions: Selectively prune trees and shrubs to allow more light and air to reach the grass. Avoid mowing turf too short. Water infrequently but deeply. Apply Soap-Shield to areas with a history of powdery mildew.
Asochyta Leaf Blight
Symptoms: Large areas of turf may assume a uniformly blighted appearance, or smaller heavily infected patches appear blighted. It survives in debris and is spread during wet periods. The fungus generally infects the blade through freshly mowed blade ends. Ascochyta leaf blight can occur at any time of year.
Solutions: Water as little as possible. Avoid excessive nitrogen fertilization, but use Lawns Alive! or WOW! Plus to maintain active, healthy grass growth. Apply Soap-Shield at first appearance where the disease occurred in previous years.